Abstract: At least two lineages of Mesozoic birds are known to have possessed a distinct feather morphotype for which there is no neornithine (modern) equivalent. The early stepwise evolution of apparently modern feathers occurred within Maniraptora, basal to the avian transition, with asymmetrical pennaceous feathers suited for flight present in the most basal recognized avian, Archaeopteryx lithographica. The number of extinct primitive feather morphotypes recognized among non-avian dinosaurs continues to increase with new discoveries; some of these re...
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Topics: 
Zoology
Evolutionary biology